no it's not cursor trails as far as i know. that's when you see an echo of the cursor kinda.. used on laptops sometimes back in the day to make it easier to find the cursor?
this is definitely an error.. because you see only the top few pixels of the cursor but it's tiled a bunch of times. and it makes it a bit difficult to see where you're clicking...and when the cursor changes, it does change but again just the top few pixels tiled down.
looks kinda like this: http://i.imgur.com/RSOi9.gif